FOUNDRY SHOP

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• Q1: Define Casting.
  Ans: Casting is a manufacturing process in which molten metal is poured into a mould cavity and allowed to solidify to get the desired shape.
• Q2: State some casting defects.
  Ans: Casting defects are as follows:

  • ➔ Blow holes
  • ➔ Shrinkage defect
  • ➔ Mis run
  • ➔ Hot tears
  • ➔ Mismatch or shift
  • ➔ Drop
  • ➔ Fins
  • ➔ Porosity
• Q3: What is Open Blow or Blow Holes?
  Ans: Blow holes are smooth, round or oval holes formed in casting due to trapped gas inside the molten metal during solidification.
• Q4: State the causes of Open Blow or Blow Holes.
  Ans: The causes of blow holes are:

  • ➔ Excess moisture in mould
  • ➔ Poor venting of mould
  • ➔ Improper melting of metal
  • ➔ Low permeability of sand
• Q5: State the remedies for Open Blow or Blow Holes.
  Ans: Remedies for blow holes are:

  • ➔ Proper drying of mould
  • ➔ Improve venting system
  • ➔ Use properly melted and cleaned metal
  • ➔ Use good permeability sand
• Q6: Define Shrinkage Defect as Casting Defect.
  Ans: Shrinkage defect is a casting defect that occurs when the metal contracts during solidification and leaves empty spaces or cavities in the casting.
• Q7: State the causes of Shrinkage Defect.
  Ans: Causes of shrinkage defect:

  • ➔ Improper feeding of molten metal
  • ➔ Poor design of casting
  • ➔ Lack of risers
  • ➔ Uneven cooling rate
• Q8: State the remedies for Shrinkage Defect.
  Ans: Remedies for shrinkage defect:

  • ➔ Proper use of risers
  • ➔ Improve casting design
  • ➔ Ensure uniform cooling
  • ➔ Proper feeding of molten metal
• Q9: Define Mis Run as Casting Defect.
  Ans: Mis run is a casting defect in which molten metal solidifies before completely filling the mould cavity.
• Q10: State the causes of Mis Run.
  Ans: Causes of mis run:

  • ➔ Low pouring temperature
  • ➔ Thin sections in mould
  • ➔ Poor fluidity of metal
  • ➔ Slow pouring rate
• Q11: State the remedies for Mis Run.
  Ans: Remedies for mis run:

  • ➔ Increase pouring temperature
  • ➔ Improve mould design
  • ➔ Increase metal fluidity
  • ➔ Proper and fast pouring
• Q12: Define Hot Tears as Casting Defect.
  Ans: Hot tears are cracks formed in casting during cooling due to internal stresses when the metal is weak at high temperature.
• Q13: State the causes of Hot Tears.
  Ans: Causes of hot tears:

  • ➔ Uneven cooling of casting
  • ➔ Poor mould design
  • ➔ High restraint in contraction
  • ➔ Weak hot strength of metal
• Q14: State the remedies for Hot Tears.
  Ans: Remedies for hot tears:

  • ➔ Improve casting design
  • ➔ Ensure uniform cooling
  • ➔ Reduce sharp corners in design
  • ➔ Use proper alloy composition
• Q15: Define Shift or Mismatch as Casting Defect.
  Ans: Shift or mismatch is a casting defect in which the two halves of the mould are not properly aligned, causing a step or displacement in the casting.
• Q16: State the causes of Shift or Mismatch.
  Ans: Causes of shift or mismatch:

  • ➔ Improper alignment of mould halves
  • ➔ Loose fitting of mould box
  • ➔ Incorrect pattern mounting
  • ➔ Rough handling of mould
• Q17: State the remedies for Shift or Mismatch.
  Ans: Remedies for shift or mismatch:

  • ➔ Proper alignment of mould
  • ➔ Tight fitting of mould box
  • ➔ Correct pattern setting
  • ➔ Careful handling of mould
• Q18: Define Drop as Casting Defect.
  Ans: Drop is a casting defect in which a portion of the mould sand falls into the molten metal cavity and creates an unwanted projection in casting.
• Q19: State the causes of Drop.
  Ans: Causes of drop:

  • ➔ Weak mould strength
  • ➔ Poor ramming of sand
  • ➔ Improper support of mould
  • ➔ Rough handling
• Q20: State the remedies for Drop.
  Ans: Remedies for drop:

  • ➔ Proper ramming of sand
  • ➔ Improve mould strength
  • ➔ Provide proper support
  • ➔ Careful handling of mould
• Q21: Define Fins as Casting Defect.
  Ans: Fins are thin unwanted projections of metal formed at the joint of mould halves due to leakage of molten metal.
• Q22: State the causes of Fins.
  Ans: Causes of fins:

  • ➔ Improper closing of mould
  • ➔ Poor alignment of mould parts
  • ➔ Excessive fluidity of metal
  • ➔ Worn out pattern
• Q23: State the remedies for Fins.
  Ans: Remedies for fins:

  • ➔ Proper alignment of mould
  • ➔ Tight closing of mould
  • ➔ Use good quality pattern
  • ➔ Control metal fluidity
• Q24: Define Porosity as Casting Defect.
  Ans: Porosity is a casting defect in which small holes or voids are formed inside the casting due to trapped gas or shrinkage.
• Q25: State the causes of Porosity.
  Ans: Causes of porosity:

  • ➔ Gas entrapment in molten metal
  • ➔ Improper venting
  • ➔ Moisture in mould
  • ➔ Contaminated metal
• Q26: State the remedies for Porosity.
  Ans: Remedies for porosity:

  • ➔ Proper venting of mould
  • ➔ Use dry mould materials
  • ➔ Clean molten metal
  • ➔ Proper degassing of metal